1. Field of the Invention
The present invention relates to an air bag module of an air bag system for a vehicle, and more particularly, to a cushion of an air bag module which can normally deploy the cushion and prevent a deployment time delay phenomenon by enhancing the flow of gas supplied into the cushion.
2. Description of the Background Art
Generally, an air bag system for a vehicle is a safety device for inflating an air bag module like a balloon upon the occurrence of a vehicle collision to thus alleviate an impact to a passenger and prevent the passenger from being thrown out of the vehicle by the cushioning action of an air bag module.
Such an air bag system for a vehicle is classified into a number of types, including a driver air bag (DAB) and a passenger air bag (PAB) for protecting front seat passengers at the time of a front collision of a vehicle and a side air bag (SAB) for protecting a passenger in the ribs at the time of a side collision of a vehicle.
In the aforementioned air bag system for a vehicle, the deployment pattern of the air bag module is determined according to the movement direction of a human body at the time of a vehicle collision. Typically, the driver air bag and the passenger air bag are designed to have a near-round deployment pattern, while the side air bag is designed to have a linear deployment pattern.
FIG. 1 is an exploded perspective view showing a mounting structure of a conventional side air bag for a vehicle.
As shown in FIG. 1, the conventional side air bag for a vehicle includes an air bag module 2 for protecting an occupant of the vehicle and an air bag housing 4 for storing the air bag module 2 and being mounted to a seat frame 8 of a seat back 6.
The air bag module 2 includes an inflator 3 for generating a high pressure gas in the event of a vehicle collision, an inflator housing 12 having the inflator 10 installed therein, and a cushion 14 made of a fabric and deploying toward a passenger upon being supplied with the high pressure gas from the inflator 10.
FIG. 2 is a cross sectional view shoving a cushion of an air bag module according to the prior art.
The cushion 14 of the air bag module 2 according to the prior art is provided with a thorax chamber 20 which deploys toward the chest of the occupant, a head chamber part 22 which is formed to communicate with the thorax chamber part 20 and deploys toward the head of the occupant upon being supplied with gas in the thorax chamber part 20, and an inner pocket 24 which is mounted on an inner side of the thorax chamber part 20 for introducing a high pressure gas from the inflator 10, and which has vent holes 30 for emitting the gas into the thorax chamber part 20.
A barrier 26 is formed between the thorax chamber part 20 and the head chamber part 22, and the barrier 26 has a plurality of through holes 30 for supplying the gas in the thorax chamber part 20 into the head chamber part 22.
In this manner, the cushion 14 of the air bag module 2 is formed in a dual chamber structure such that damage to the cushion 14 can be prevented and the cushion 14 can deploy to a proper position according to the movement direction of the occupant in the event of a vehicle collision.
The operation of the thus-formed cushion of the air bag module according to the prior art will be described below.
Firstly, in the event of an accident, such as a collision or turnover of a vehicle, the accident, such as a collision or turnover, is sensed by a collision sensor (not shown) installed in the vehicle, and then a sensing signal is transmitted to an electronic control unit (not shown) of the vehicle, and a side air bag for a vehicle is operated by the signal of the electronic control unit.
In other words, when a side collision of a vehicle is sensed by the collision sensor, a high pressure gas is generated by the inflator 10 that has receive a signal from the electronic control unit, the high pressure gas is delivered to the inner pocket 24 in the thorax chamber part 20, and the gas decelerated or compressed in the inner pocket 24 is emitted into of the thorax chamber part 20 through the vent holes 30.
The thorax chamber part 20 deploys toward the chest of the occupant by the high pressure gas, the gas emitted into the thorax chamber part 20 is delivered into the head chamber part 22, and the head chamber part 22 deploys toward the head of the occupant.
However, in the cushion 14 of the air bag module 2 according to the prior art, since the thorax chamber part 20 directly deploys toward the chest of the occupant by the dynamic pressure of the gas emitted from the inner pocket 24, or the head chamber unit 22 deploys in a different direction than that of the gas emitted from the inner pocket 24, the gas is supplied into the head chamber part 22 at the point of time when the deployment of the thorax chamber part 20 is almost finished.
That is, the static pressure of the gas emitted into the thorax chamber part 20 reaches more than a predetermined value, the head chamber part 22 deploys toward the head of the occupant by the dynamic pressure of the gas introduced through the through holes 30 of the barrier 26.
As seen from above, the cushion 14 of the air bag module 2 is problematic in that it is not possible to deploy the head chamber part 22 until the static pressure of the gas emitted into the thorax chamber part 20 reaches a predetermined value, and the static pressure is converted into a dynamic pressure in the direction of the head chamber part 22 after the dynamic pressure of the gas is converted into a static pressure in the thorax chamber part 20, thereby causing an energy loss.
Moreover, the loss of mechanical energy occurs in the procedure of the gas flowing into the head chamber part 22 from the inner pocket 24, and hence the head chamber part 22 does not deploy smoothly and the deployment time of the head chamber part 22 is delayed.
As above, if the head chamber part 22 is not deployed in a precise shape at a proper time, the driver and the passenger are not effectively protected by the air bag module 2 in the event of a vehicle collision, which deteriorates the reliability and merchantability of the air bag system for a vehicle.